Lighting devices, such as headlamps, the same as other automotive parts, usually require some linear setting.
This setting is carried out by means of adjusters. This pieces usually comprise a shaft which is able to move linearly. By this linear movement of the shaft, and a balancing rod connected to the end of the shaft and to the piece to be adjusted, the latter may be adjusted.
In these adjusters, the shaft is usually moved by a gear movement. This gear movement is easily controlled by a movement of the user. But when the output shaft reaches a predetermined limit position, the gear movement must be uncoupled from the shaft movement, so as to avoid damaging the piece to be adjusted.
This uncoupling is usually detected by an increase in the torque needed to make the output shaft exit beyond its limit position. This increase in the required torque is detected by a piece which uncouples the gear and the shaft. An example of such a torque limiting adjuster is found in document U.S. Pat. No. 7,198,392 B2. In this document, an adjuster is disclosed, comprising an output shaft, a drive gear, a threaded portion, a threaded sleeve, a spring and a driven gear that allow the headlamp adjuster to clutch. When a maximum value of torque is reached, the drive gear will force the driven gear to slide on and along an external spline of the threaded sleeve, thereby compressing the spring. The driven gear will continue to slide away from the drive gear until the drive gear is no longer engaged with the driven gear.
An alternative device for such purpose is provided by the present disclosure. This alternative device aims at reducing the number of parts, thus achieving a simpler device and a less expensive manufacturing and maintenance.